The purpose of this study is to confirm the clinical benefit observed in the pivotal registration study, Hx-CD20-406. The Committee for Medicinal Products for Human Use (CHMP) required that a randomized study be conducted in CLL patients with bulky fludarabine-refractory disease as a specific obligation for grant of conditional approval for ARZERRA™ in the European Union (EU). This study will compare ofatumumab with the physicians' choice of therapy.